Actuator end stop arrangement

ABSTRACT

The arrangement comprises a stop bar (1) formed from a cylindrical rod having a lengthwise slot therein. The stop bar (1) is secured to a fixed support within an actuator casing (7). A stop plate (15) is slidably secured in the slot and presents upper and lower stop edge portions (16, 17) for engagement with spaced limbs (23) of arm means for converting linear motion into angular motion. The position of the stop edge portions (16, 17) relative to the stop bar (1) is adjustable by means of replaceable shims (21) in the slot.

BACKGROUND OF THE INVENTION

This invention relates to an actuator end stop arrangement and moreparticularly, for an actuator wherein linear motion is converted toangular motion, an end stop arrangement for the angular motion of an armmeans which is driven by linear motion and delivers angular motion to ashaft.

The conventional end stop arrangement comprises large adjustment screwsand lock nuts. However, such arrangements take up a great deal of spaceand it is an object of the invention to provide a simple constructionwhich is effective and takes up less space than the conventionalarrangement.

SUMMARY OF THE INVENTION

According to the invention, there is provided, an end stop arrangementfor the angular motion of an arm means in an actuator wherein linearmotion is received by the arm means and is converted by the arm meansinto angular motion and delivers such angular motion to a shaft, thearrangement comprising an assembly of a stop bar formed from acylindrical rod but having a lengthwise slot therein, means for securingthe stop bar to a fixed support within the actuator casing both in asense lengthwise of the stop bar and angularly about its axis, a stopplate slidably secured in the slot and presenting a stop edge forengagement with the arm means, the position of the stop edge relative tothe stop bar being adjustable by the insertion or removal of spacermeans in the slot and engaging an edge of the stop plate remote from thestop edge.

BRIEF DESCRIPTION OF THE DRAWING

An embodiment of the invention will now be described, by way of example,with reference to the accompanying drawing, in which:

FIG. 1 is an elevation, partially in section, of an end stoparrangement, according to the invention, assembled in position in afixed support within an actuator casing and shown in contact with armmeans of the actuator; and

FIG. 2 in a section, to an enlarged scale, on line II--II in FIG. 1.

DESCRIPTION OF THE PREFERRED EMBODIMENT

In the drawing, a stop bar 1 is formed from a cylindrical rod. Alengthwise slot 2 is cut in the stop bar 1. As shown, the bar I isrelieved at each side of the slot 2 to provide two parallel wings 3. Twopairs of aligned holes are provided through the wings 3 near the upperand lower ends of the stop bar 1.

A cylindrical end part 4 is welded to the bottom end of the stop bar 1and has an annular groove receiving an 0-ring 5 sealing a bottom bore 6in the actuator casing 7. The bottom bore 6 has a shoulder 8 againstwhich the end part 4 seats. The casing 7 also has an intermediate boreand an upper bore 10 aligned with the bore 6 and the stop bar 1 ishoused within all three bores A cap 11 is bolted at 12 to the casing 7and covers the bore 10. The cap 11 has a spigot 13 which enters the bore10 and engages the upper end surface of the stop bar 1. A location peg14 extends from the spigot 13 into the slot 2. Thus the stop bar 1 issecured in a lengthwise sense and in an angular sense.

A stop plate 15 is housed in the slot 1 and presents an upper stop edgeportion 16 between the bores 9 and 10, a lower stop edge portion 17between the bores 6 and 9, and a relief intermediate the edge portions16, 17 and registering with the intermediate bore 9. On one side of theplate 15 adjacent to each edge 16, 17 is a circular recess 18 whichreceives a disc spring 19 slidably securing the plate 15 in the slot 2.Endwise movement of the plate 15 is limited by pins 20 inserted in thealigned holes in the wings 3 and spanning the slot 2. The position ofthe stop edge portions 16, 17 relative to the stop bar 1 is adjusted bythe insertion or removal of spacer shims 21 in the slot 2 and engagingthe edge 22 of the stop plate 15 remote from the stop edge portion 16,17.

In FIG. 1 the arm means of the actuator is shown as two spaced limbs 23of yoke which has an angular motion.

The end stop arrangement is assembled as follows. The disc springs 19are located in the recesses 18. The pins 20 are fitted to the stopbar 1. The stop plate 15 and located disc springs 19 are insertedlaterally into the slot between the pins 20. The stop bar 1, with itsbottom end part 4, is inserted into the aligned bores 6, 9, 10 fromabove until seated on the shoulder 8. The stop plate 15 is pushed fullyinto the slot 2 so that the plate clears the bores. With the yoke limbs23 clear of the end stop arrangement, the stop plate 15 is leveredoutwards of the slot 2 and the required number of shims 21 is insertedinto the space left in the slot 2 from above. Any surplus shims 21 areinserted in the spaces on the outer sides of the wings 3 ready forpossible future use. The stop bar 1 is turned to its correct angularposition and the cap 11 is applied with the spigot 13 entering the bore10 and the peg 14 entering the slot 2.

In a modification the part 4 may be replaced by a cap similar to cap 11with or without the peg 14.

It will be noted that the arrangement described and illustrated cannotlose adjustment between the limbs 23 as could happen with screws andnuts in the conventional arrangement.

Claim:
 1. An end stop arrangement for angular motion of an arm means inan actuator wherein linear motion is received by the arm means and isconverted by the arm means into angular motion and delivers such angularmotion to a shaft, the arrangement comprising an assembly of a stop barformed from a cylindrical rod but having a lengthwise slot therein,securing means for securing the stop bar to a fixed support within theactuator casing both in a sense lengthwise of the stop bar and angularlyabout its axis, a stop plate slidably secured in the slot and presentinga stop edge for engagement with the arm means, the position of the stopedge relative to the stop bar being adjustable by the insertion orremoval of the spacer means in the slot and engaging an edge of the stopplate remote from the stop edge.
 2. An end stop arrangement according toclaim 1, wherein the slot opens into at least one end of the stop bar,the slot has an open end, the securing means comprises a cap for closingthe open end of the slot, the stop plate is so dimensioned as to befully receivable in the slot in the absence of the spacer means, and thespacer means are in the form of shims which are insertable into the slotfrom said open end of said slot after the assembled stop bar and stopplate has been installed in the actuator casing and the stop plate hasbeen partially levered out of the slot, but before the cap has beeninstalled.
 3. An end stop arrangement according to claim 2, wherein thestop bar is relieved at each side of the slot to provide two parallelwings leaving spaces for housing surplus shims.
 4. An end stoparrangement according to claim 1, wherein the actuator housing has threealigned bores, the arm means includes two spaced limbs, the stop edge ofthe stop plate has upper and lower stop edge portions interrupted by anintermediate relief, the intermediate relief is positioned to registerwith an intermediate one of the three aligned bores in the actuatorhousing, the upper and lower stop edge portions of the stop edge beingpositioned to be engaged on both sides of the intermediate bore by thetwo spaced limbs of the arm means.